Light bulb



FIG. 1 is a perspective view of a light bulb showing our new design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a left side view thereof; and,

FIG. 7 is a right side view thereof

The broken lines herein show environmental structure and form no part of the claimed design. 

The ornamental design for a light bulb, as shown and described. 